Hand operated tools

ABSTRACT

A hand-operated tool for imparting unidirectional rotational drive to a screw-thread fastener or the like includes a triggeractuated drive mechanism for converting linear motion of the trigger of the tool into rotaty movement of the tool bit holder and an adjustable torque-limiting clutch acting between the trigger-actuated drive-mechanism and the tool bit holder.

United States Patent [1 1 Bieganski HAND OPERATED TOOLS [76] Inventor: Zdzislaw Bieganski,-Apem Works, St. Albans Rd., Watford, England [22] Filed: Jan. 21, 1974 [21] Appl. No.: 434,909

[30] Foreign Application Priority Data Jan. 19, 1973 Great Britain 2827/73 [52] US. Cl 81/52.4 R [51] Int. Cl. ..L B25b [58] Field of Search 81/524 R, 57.39

[56] References Cited UNITED STATES PATENTS 3,756,090 9/1973 Mella et al 81/5739 2o 3,2 go

[ Jan. 14, 1975 Primary Examiner-James L. Jones, Jr. Attorney, Agent, or FirmMarshall & Yeasting [57] ABSTRACT A hand-operated tool for imparting unidirectional rotational drive to a screw-thread fastener or the like includes a trigger-actuated drive mechanism for converting linear motion of the trigger of the tool into rotaty movement of the tool bit holder and an adjustable torque-limiting clutch acting between the triggeractuated drive-mechanism and the tool bit holder.

8 Claims, 1 Drawing Figure HAND OPERATED TOOLS This invention relates to hand-operated tools of the kind in which a tool bit such as a screw driver or an Allen key is to be rotated uni-directionally, as is required for example in the assembly of components held together by screws.

The object of the invention is to provide a convenient compact tool for this purpose.

In accordance with'the invention, a hand-operated tool comprises a butt having a rack and pinion mechanism with the rack displaceable against a return spring by a trigger, and the pinion connected by a one-way clutch to a worm and pinion providing a unidirectionally rotatable final drive shaft, said shaft being connected via an adjustable torque clutch to one part of areleasable coupling, and at least one tool bit provided with a second part of said coupling for interchangeable connection therewith.

One presently preferred embodiment of the invention willnow be more particularly described with reference to the accompanying drawing wherein the sole FIGURE is an elevation, partly in section, of a complete tool.

Referring now to the drawing, the tool comprises a butt carrying a trigger 12 which is integral with a rack 14 and has a parallel guide stem 16, both the rack and the stern being urged by coiled compression springs 18 so as to project from the butt, and being reciprocable towards the butt so as to rotate pinion 20 which is journalled in the butt.

The pinion is fast with the rotor 22 forming the hub of a one-way clutchand the rotor is trapped in a large pinion 24 and a number of balls or rollers 26 are arranged so that in travel of the hub in a clockwise direction (as illustrated) the rollers wedge or jam and transmit motion to the pinion 24, and during return of the rack by the springs, the balls or rollers free and allow the hub to rotate relative to the pinion 24 in the opposite direction.

Pinion 24 is meshed with worm 26 carried on a shaft assembly 28 and journalled in the barrel of the pistol-like tool by spaced bearings and bushes 30, 32.

The shaft 28 is provided with a hardened insert 34 which is generally annular and has a series of ball accommodating recesses provided in an end face.

Carried by the shaft 28 is a final drive shaft 36 which is journalled in an end portion of theshaft 28 by a fur ther bush 32 and has similar ball accommodating recesses in the end face adjacent the hardened insert and a series of balls 38 is trapped between the two sets of recesses.

A torque adjusting screw assembly is located axially of the arrangement with the shank40 of the screw engaged with a threaded portion 42 of the shaft 28, with a ball race 44 trapped between the head of the screw and a compression spring 46 and the spring abutting a shoulder 48 in the final portion 36.

The portion 36 is provided with a female coupling part for example comprising pins 52 and spring 54 so that a tool bit comprising coupling part 56 and bit proper 58 can be inserted in the end part of the final drive assembly 36 and engaged therewith for rotation therewith, or released therefrom and spring ejected.

In use, reciprocation of the trigger 12 causes the shaft 28 to rotate uni-directionally, and the balls 38 transmit this rotational drive to the assembly 36 and hence to the tool 56, 58. The torque transmitted between the shafts 28, 36 is dependent upon the setting of the screw 40 and the spring pressure applied by spring 46 and can be varied by for example removing the tool 56, 58 and inserting a screw driver so as to rotate the screw 40. This increases the spring loading urging the recessed faces together and trapping the balls, since the clutch afforded thereby becomes a slipping clutch when the part 36 moves axially with respect to the part 28 against the spring 46, and the balls move (preferably with the part 36) relative to the hardened insert 34.

I claim:

1. A hand-operated tool comprising a butt having a rack and pinion mechanism with the rack displaceable against a return spring by a trigger, and the pinion connected by a one-way clutch to a worm and pinion providing a uni-directionally rotatable final drive shaft, said shaft being connected via an adjustable torque clutch to one part of a releasable coupling, and at least one tool bit provided with a second part of said cou pling for interchangeable connection therewith.

2. A tool as claimed in claim 1 wherein the trigger is provided with a guide stem parallel to the rack, and both rack and guide stem are urged in the same direction by compression. springs.

3. A tool as claimed in claim 1 wherein the one-way clutch comprises a pinion engaged with the rack and fast with the hub, and a series of balls or rollers located between the hub and the pinion which is engaged with the worm, the contour of the hub being such that in one direction of rotation the balls or rollers render the hub and worm pinion fast together, and in the opposite direction of rotation of the rack pinion the balls or rollers move relative to the worm pinion. i

4. A tool as claimed in claim 1 wherein said final drive shaft comprises a pair of parts with said adjustable torque clutch between the two.

5. A tool as claimed in claim 4 wherein the adjustable torque clutch comprises confronting faces on said pair of parts, a plurality of coupling balls located in recesses in said faces, and spring means urging the faces towards one another.

6. A tool as claimed in claim 5 wherein said spring means comprise a helical compression spring located in the bore of one of the parts, a screw extending through said spring and compressing the same, the screw being engaged with the otherof the parts.

7. A tool as claimed in claim 6 wherein a ball race is located between the head of the screw and the spring.

8. A tool as claimed in claim 1 wherein the releasable coupling comprises an ejector spring; 

1. A hand-operated tool comprising a butt having a rack and pinion mechanism with the rack displaceable against a return spring by a trigger, and the pinion connected by a one-way clutch to a worm and pinion providing a uni-directionally rotatable final drive shaft, said shaft being connected via an adjustable torque clutch to one part of a releasable coupling, and at least one tool bit provided with a second part of said coupling for interchangeable connection therewith.
 2. A tool as claimed in claim 1 wherein the trigger is provided with a guide stem parallel to the rack, and both rack and guide stem are urged in the same direction by compression springs.
 3. A tool as claimed in claim 1 wherein the one-way clutch comprises a pinion engaged with the rack and fast with the hub, and a series of balls or rollers located between the hub and the pinion which is engaged with the worm, the contour of the hub being such that in one direction of rotation the balls or rollers render the hub and worm pinion fast together, and in the opposite direction of rotation of the rack pinion the balls or rollers move relative to the worm pinion.
 4. A tool as claimed in claim 1 wherein said final drive shaft comprises a pair of parts with said adjustable torque clutch between the two.
 5. A tool as claimed in claim 4 wherein the adjustable torque clutch comprises confronting faces on said pair of parts, a plurality of coupling balls located in recesses in said faces, and spring means urging the faces towards one another.
 6. A tool as claimed in claim 5 wherein said spring means comprise a helical compression spring located in the bore of one of the parts, a screw extending through said spring and compressing the same, the screw being engaged with the other of the parts.
 7. A tool as claimed in claim 6 wherein a ball race is located between the head of the screw and the spring.
 8. A tool as claimed in claim 1 wherein the releasable coupling comprises an ejector spring. 